Method of increasing the volumetric efficiency of cylinder and piston machines.



N A: VOGT. METHOD OF INCREASING THE VOLUMETRIO EFFICIENCY OF CYLINDER AND PISTON MACHINES.

urnmnmn rmm JAN. 21, 1901. 899,706. Patented Sept. 29, 1908.

2 SHEETS-SHEBT l.

Witnesses. v Inventor. wzfm,

v A. VOGT. METHOD OF INGREASING THE VOLUME-TRIO EFFICIENCY OF CYLINDER AND PISTON MACHINES- .APPLIOATION FILED JAN. 21,1907.

. 9,706. Patented Sept. 29, 1908.

2 SHEETS-SHEET 2| Witnesses. Q Inventor.

. piston, or in other UNITED STATIEQIZAETENT orrron ADOLF VOGT, OF LONDON, ENGLAND.

ME'rIIon 0F INCREASING THE VOLUMETRIG EFFICIENCY OF CYLINDER AND PISTON MACHINES.

Specification of Letters Patent.

Patented Sept. 29, 1908.

Application filed January 21, 1907. Serial No. 353,340.

To all whom it may concern:

Be it known that I, ADoLF Veer, a citizen of AustriaHungary, residing at 1491Tulse Hill, in the county of London, England, electrician, have invented a certain new and useful Method of Increasing the Volumetric Efliciency of Cylinder and Piston Machines, of which the following is a specification.

Machines wherein a piston working in a cylinder draws in a charge of elastic fluid, such as pumps, compressors, four-strokecycle internal combustion engines and the like, can at best draw in during the suction stroke a quantity of fluid such as air or gas which is equal to the capacity of that part of the cylinder which is passed through by the words, the volume of the stroke. In practice however when the fluid does not enter under pressure above that of the atmosphere, this quantity isnever attained, and in cases where the pistonmoves at a high velocity the amount drawn in falls as low as -50 per cent. or even less, of this volume.

My invention has for its object to enable such cylinder and piston machines to draw in more air or gas than corresponds to the volume of the stroke, even when the piston travels at the highest speeds. Forthis purpose, in the case of an ordinary four-strokecycle internal combustion engine in which a suction stroke draws in a new charge, the

suction pipe is made suiiiciently narrow and long, and the inlet valve is operated in such manner as to cause a partial vacuum 1n the cylinder during theinitial part of the suction stroke so that the air column will enter at a high velocity and will by reason of the kinetic energy of the moving column continue to enter the cylinder even after the internal pressure becomes equal to that of theatmosphere. Thus, when or before the air column comes to a standstill the pressure of the charge before the compression stroke will exceed atmospheric pressure and may exceed it very considerably.

When the suction valve is closed the excess pressure at the closed end of the suction pipe will cause the column of air to surge backward towards the open end, thereby producing a diminishing pressure at the closed end and an if the suction valve is closed a moment when the air the inlet of the first increasing pressure towards the open end. Consequently a pulsating column will be established in the suction pipe consisting of alternatin waves of condensation and rarefaction in t 1e manner of an or an pipe closed at one end, the wave length (Iepending on the length of the pipe. It will be obvious therefore that by giving a proper value to the length of the pipefor any given engine, which value will depend primarily on the stroke speed of the piston, the suction valve can be arranged to open at column is surging inwardly towards the suction valve or port and consequently this initial velocity of the entering air column will assist the entering charge to follow up the movement of the pis: ton and contribute to filling the cylinder with a charge of air which Wlll be considerably in excess of the stroke volume of the cylinder. As in motor engines of this class the maximum useful eil'ect is dependent upon the volume of the charge in the cylinder it will be evident that by the above described mode of operating, the useful eiiect greatly increased. Ex-

of an engine can be periments have shown that by-thls means instead of a charge only equal to 85 p. c. of the stroke volume, a cylinder charge equalto about'130 tained.

In applying the invention to pum s or compressors running at a high spee the pump is, according to one arrangement, constructed with only a discharge valve, which is preferably made as large as or even larger than the diameter of the cylinder, while for the fluid slots are formed in the cylinder walls which are opened and closed by the piston and are so arranged that during part. of the pistons stroke they are closed and consequently a partial vacuum is produced in the cylinder. As soon as the piston uncovers the slots the air or other fluid under atmospheric pressure rushes into the cylinder at a speed which increases until an equilibrium of'pressure has been established, whereupon the )ressure of the cylinder-charge will be raised above that of the atmosphere in the same manner as above described. The arrangement is such that the piston closes the slots again at the moment p. c. of such volume can be 0bwhen the maximum pressure has been attained. The column of air in the suction pipe will then rebound towards the outside, thereby momentarily causing a certain degree of vacuum in the part next the slots, and an oscillating motion will thus be set up in the air column. The diagrams Figures 4 and 5 shown on the-drawing to be presently de scribed, clearly indicate this action. With a correctly proportioned length of the air column in the suction pipe, it will swing towards the cylinder slots at the moment that these are uncovered by the piston. The end motion of this oscillation of the column will be Very slow, as shown by the diagrams. When employing such pumps for gas turbines, as for exam le for the construction described in the speci cation to my pending U. S. application No. 317,591, where it is desired to compress to a very high degree, such as 25 atm. in one stage, it is preferable to inject water into the air drawn in, so that the charge will thenileave the pump at a temperature corresponding to that of'the saturated steam at the maximum pressu e in the pump. If the pump is of upright construction and there 1s an excess of water sup )ly this will accumulate on the piston, which water will be at once evaporated at the commencement of the pistons down stroke, in consequence of the decrease of ressure, so that during such stroke no comp ete vacuum will be produced, and a corresponding economy in the Work will be effected. Towards the end of the stroke the steam will be more or less condensed on the cold cylinder walls, in a similar manner to the action of a pulsometer, and

on the 'inrush of the next charge of air and water spray its condensation will be completed.

By the above described method of operating pumps or compressors can be worked very efficiently at high velocities and can be made to compress air in a single stage to from 20 to 30 atmospheres.

It will be seen that by means ofthe above described improved method of operating the advantages are gained, on the one hand of being able to supply a. much larger quantity of compressed air, or other fluid even, when working at maximum speeds, than with the ordinary arrangements; and on the other hand a considerable decrease of weight and cost of the apparatus and an increase of mechanical efficiency is obtained.

For reducing the noise caused-by the inrush of air' there may be provided on the end of the suction pipe a sound deadener similar to the exhaust silencers of internal combustion motors.

On the drawings Fig. 1 shows by way of example a vertical section, of a compressing pump constructed according to my invention, the cylinder a being provided with. air

inlet slots at li, which are controlled by the piston c d," is the discharge valve, seated di- 1 rectly upon the end of the cylinder; 0 is the air suction pipe and f the discharge branch for the compressed air.

Fig. 2 shows an indicator diagram for a pump such as above described when running at 300 revolutions per minute, the scale of the indicator spring being 10 m. 111. 2.8 atm.

Fig. 3 shows a governing diagram for 265 revolutions per minute, the scale of spring being the same as at Fig. 2. The work of the pump is in this case regulated by means of a throttle valve in the suction pipe.

Fig. 4 shows a diagram of the oscillations of the air column, the length of the column being 4.4 m.,with a speed of 120 revolutions per minute; the scale of the indicator spring is 20 m.m. 1 atm.

Fig. 5 shows a diagram of the column oscillations when the length of the column is 9.9 m. the speed and scale of the spring being the same as at Fig. 4.

I claim:

1. A method of increasing the volumetric efliciency of cylinder and piston machines drawing in charges of elastic lluid, which consists in causing the suction to occur through a pipe of such length that the pressure at the inlet port at the moment of closing is greater than the normal pressure of the fluid at said port.

2. A method of increasing the volumetric efficiency of cylinder and piston machines drawing in charges of elastic lluid, consisting in causing the suction to occur through a pipe of such dimensions that the oscillations set up in the column of elastic lluid therein are so timed that when the suction port is closed, the pressure toward the suction port of the'elastlc fluid due to the etl'eet ol the inertia of the column is at or near its maximum, substantially as described.

3. A method of increasing the volumetric efficiency of cylinder and piston machines drawing in charges of elastic iluid, consisting in causing the suction to occur through a pipe of such dimensions that the oscillations set up in the column of elastic fluid therein are so timed that when the suction port is closed, the pressure toward the suction port of the elastic lluid due to the ell'eet ol' the inertia of the column is at or near its maximum and introducing such an excess of cooling water into the machine that part of the water evaporates in the cylinder during the suction stroke and is subsequently con-- densed, substantially as described.

4. A method of increasing the volumetric efficiency of cylinder and piston machines drawing in charges of elastic lluid, which comprises causing the elastic lluid to more in a column toward the inletfporlaand giving li t) lffll said column a substantially maximum pres- I name '06 this specific'ation in the-presence of sure node at the moment of closing 'of the intwo subscribing witnesses. let port, thereby'producing a pressure within v the cylinder at the time of closure of the port '5 greater than the normal pressure of theelastic fluid.

Iu testi mo'ny whereof I heve signed my v ADOLF VOGT.

Witfiesses:

' OLIVER IMRAY, J {PHILLIPS CRAWLEY. 

